I normally take my road trips for holidays. But when I do it it is the long haul drive. I also have a 72 pound Lab that goes with me. The last few trips that I have done like this I have made sure that I have healthy food in the cooler. Also, if you want a good idea for keeping food cold for say 10-12 hours and then you can refreeze them. Those popciles that come in plastic. They are at the grocery during the summer. You can pick up a box for like 3.00. Once you are done with the road trip, you refreeze them and eat them.
When I know it is a trip like this I also know that I want to be on the road the shortest time possible. I will stop to get gas and let the dog do his business. Then on the road again. I will make sandwiches and eat while driving. I will sometimes get some of the small bags of chips to bring along too. It is too easy to mindlessly snack while driving.
Packing for vacations for me is also different. If I know that I'm going somewhere that I will likely buy stuff to bring home I will make sure that the pants I have are comfortable, Because they will be worn 2 to 3 times depending on the length of the trip. So then I get away with 2 pairs of pants. I like to have fresh tee shirts One per day + 2 extra. underware for everyday, socks for everyday+2. I always take a couple longsleeve shirts and a rain coat that will pack into its own pocket.
When I travel in europe and limit myself to a backpack, I might reduce down from there.
There is a hemp castille soap that I travel with in europe too. It is good to use for everything. I used it for soap, shampoo, toothpaste. It doesn't taste great, but then my toiletries are reduced to: bottle of castille, toothbrush with half a handle, DO, a comb and a razor. The castille works for shaving cream too. I also will only have my hiking style tennis shoes and a pair of croc's. Croc's are fantastic foam "clogs" that free great to slip on after a day of hiking around a city. When I'm home they are worn to grab the mail, take the dog out, I like cooking in them too. Plus they come in about any color you can imagine.
The space I save in my backpack normally gets filled with stuff like french wine from Bordeaux or the Rhine river valley in Germany, or that bottle of Brunello that I got in Florence.
If am going to a specific city and plan on being there for most of the trip I will pack my bike messenger bag. It is a great catchall bag for travel. It gets camera, journal for daily updates and scetching, maps, the raincoat and maps. If you buy anything it is big enough to toss stuff in too. Also don't limit yourself to eating out all the time. Get to a grocery and pick up things that you can take with you while you are out an about. I like to carry a Nalgena bottle. Fill it up with water in the morning before you head out. One less thing to have to buy while you are wandering around a city you might only get a couple days in.
Wow I started rambling.